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Re: Sphere/Toroid Comparison Chart

Original poster: "Kurt Schraner by way of Terry Fritz <twftesla-at-uswest-dot-net>" <k.schraner-at-datacomm.ch>

Hi Luc, Bart,

...you are right Luc, of course! - I did an E-Tesla6 calculation for a
small coil (2"/10" secondary), supposing a 12"/4" vs. a 12"/6" toroid,
and got:

          Problem:  Medhurst    E-Tesla6    Diff=~
d1   d2   C.bert.P.  C.sec.     C.total     C.toro  Fres  
(inches)   pF         pF         pF          pF      kHz
12"  4"   13.262     4.153      15.116      10.963  522.27
12"  6"   11.585     4.153      16.350      12.197  502.17

Up to now, I was very close to the measurements on my coils, with Bert
Pools equation. But those were not in the same range of toroid data. So,
reading your first poster, was not recognized well enough (by me). I
guess, we are just outside of the validity limits for the (probably-; if
Bert is reading, he might comment!) semi-empirical Bert Pool's equation.
This equation may well be continued to use in "normal" TC-design
procedures, but when it comes to somehow extreme toroids or toroid vs.
secondary situations, not be the method of choice. The real things are
something like the super-cool measurements of Bart Anderson, which
obviously support the use of E-Tesla6. More of this kind of
measurements, together with the outcome of the TSSP, will probably lead
to design procedures, which are more precise, but, perhaps, more
important: applicable to a broader range of TC-parameters.

       Kurt Schraner

Tesla list wrote:
> Original poster: "Luc by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> Hi guy
> I post again the same question: If you look at the chart you'll
> see that until you hit 18" of exterior diameter the toroid with a
> thickness of 4" have more capacity than one of 6" thickness.
> Please could some of you explain to me how a toroid with an area
> bigger could have a smaller capacity. I already know that the
> surface facing the center ( the hole of the donut ) don't
> participated as far as the exterior. But the exterior of a 6"
> thick toroid is bigger than the area of a 4" one.
> Tx
> Luc Benard